USB Power Delivery for LED Lighting: a Bright Future

S2G Cool White and Warm White with USB Power Pack: 1000 Lumens, WiFi and Bluetooth.

The demand for rapid phone charging is behind the acceleration of power USB adapters and power packs. The Qualcomm Quick Charge standard allows for up to 18W, compared to the rather wimpy 2.5W of the USB 2.0 standard most commonly available. Assuming a relatively efficient LED driver, this could mean 16W of LED lighting or 100W incandescent. And if that is not enough, the new USB PD spec allows 20V at 5 A or 100W, plenty for all but the most demanding lighting application. Add to this the new Flotonix FLoatingGround (FLG) architecture and you can be looking at 95W of available LED drive or a staggering 700W equivalent Watts!

From a designer’s point of view, persuading a charger or power pack to output these higher levels is not so straightforward. Since Qualcomm builds the negotiation secrets into their proprietary chips we need to look at patents (Those by Hawawini are a good resource) and at the chips used by the charger designers ((Power Integrations CHY100 and CHY103, OnSemi NCP4371.)

Experimentation is the best way to figure out the inner workings, and in doing so we found an undocumented state which makes the flip from 5V@3A to 12V@1.5A amazingly simple. In fact all you need are two resistors and a switch!



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